Abstract:

The aims of this study are to explore the effect of ultrasonic-assisted extraction on extraction rate of flavonoids from Prunella vulgaris Linn, optimize extraction processing of flavonoids using orthogonal experiments, screen appropriate macroporous resin for flavonoid purification, and investigate the scavenging capability of flavonoids on free radicals. Results indicated that ultrasonic-assisted extraction did not increase the extraction rate of flavonoids from Prunella vulgaris Linn. The optimal extraction conditions were ethanol concentration of 50%, material-liquid ratio of 1:30, extraction temperature of 80 ℃ and extraction time of 3 h. The extraction rate of total flavonoids was up to 5.05% under the optimal conditions. Meanwhile, macroporous resin AB-8 was suitable for the separation of total flavonoids. UV-visible spectrum exhibited that flavanone and dihydroflavonol were the major components. The scavenging capability of total flavonoids from Prunella vulgaris Linn on DPPH and hydroxyl free radicals was a concentration-dependent manner, which was close to the scavenging capability of ascorbic acid and higher than that of tert-butylated hydroxyanisonle (BHA).

Key words: Prunella vulgaris Linn, flavonoids, free radical, isolation and purification